Method and apparatus for handling ferromagnetic sheets



Spt. 5, 1967 M. RICARD- 3,339,915

METHOD AND APPARATUS FOR HANDLING FERROMAGNETIC SHEETS Filed June 22,1965 INVENTOR Maurice Ricard ATTORNEYS United States Patent C) 6 Claims.(a. 271-18) The present invention relates to a method and apparatus forhandling ferromagnetic metal sheets, particularly sheets having somesubstantial flexibility. The object of the invention is to provide animproved method and apparatus for transferring such sheets from a firstlocation to a second location.

The sheets to be handled usually come in stacks. The method andapparatus of the invention provides for unstacking them one by one andtransferring them from the location of the stack to another location.

In the description which follows, the term tail end is applied to theend of the sheet, or of the stack, which is nearest to the secondlocation (to which the sheets are transferred), and the term head end tothe end farthest from it. Preparatory to being transferred, the sheetsare usually separated by a so-called fanner which by magnetic actionholds the sheets slightly apart on one or more sides. Pneumatic devicesare also in use which facilitate the separation of the sheets as theyare being gripped without first fanning them out.

Heretofore gripping has often been by pneumaticallyoperated suction cupsor by magnetic elements at the tail end. Moving has been by means ofpinch rolls which first engage the tail end of the sheet, or by means ofmagnetic conveyers, such as rolls or a conveyer belt. These devices havethe drawback that the sheet Will rub against the succeeding sheet as itis being moved. To overcome this drawback, the gripping devices havebeen increased in number and distributed over the entire sheet surface,with corresponding complications in the installation.

The use of gripping devices which engage the sheet at its tail end orover its entire length has the further disadvantage that the duration ofthe complete cycle is practically equal to the sum of the gripping andmoving times. Before the transfer system is able to engage a sheet, thepreceding sheet must have been moved clear of the unstacking or grippingarea. Thus the gripping and moving times are cumulative. Moreover, whenthe individual sheets are separated by a magnetic fanner, the downwardattraction exerted by it must be overcome when the sheets are movedabove it.

The invention provides an improved apparatus, and improved method, fortransferring flexible sheets of ferromagnetic metal from a firstlocation to a second location, which overcomes the foregoingdisadvantages. The apparatus comprises a conveyer disposed above andspaced from and extending between the two locations. The magnetassociated with the conveyer establishes a magnetic field in the spacebetween the conveyer and said locations. Means are provided for liftingthe head end portion of the flexible sheets, one at a time, from thefirst location to a position within the magnetic field where the liftedend portion of the sheet is magnetically attracted into engagement withthe conveyer, and successive portions of the sheet thereupon becomemagnetically attracted into engagement with the conveyer until theentire sheet is held magnetically in contact with the conveyer againstthe force of gravity. Means are provided for moving the conveyer fromabove the first location to the second location, whereby the sheet whichis magnetically held by the conveyer is transferred from a positionabove the first location to the second location. The conveyer in thevicinity of the second location advances the sheet beyond that region ofthe magnetic field wherein the metal of the sheet is magneticallysupported against the force of gravity, and in consequence the sheet isprogressively released from the conveyer and successive portions thereofdropped to the second location as the sheet is advanced over the secondlocation by the conveyer.

The method of the invention, which is employed in operation of the abovedescribed apparatus, involves establishing a magnetic field whichextends from above the first location to near the second locationbetween which the sheets are to be transferred. The head end portiononly of the sheets, one at a time, is lifted from the first location toa position within the magnetic field where such lifted end portion ismagnetically supported against the force of gravity. Thereuponsuccessive portions of the sheet become magnetically attracted into saidfield until the entire sheet is supported magnetically above the firstlocation. While thus supported the sheet is transferred to above thesecond location. There the sheet is advanced beyond the region of themagnetic field where the sheet is supported against the force ofgravity, and in consequence successive portions of the sheet are droppedto said second location until the entire sheet is there deposited.

There may be one continuous zone of magnetic attraction that extends inboth the longitudinal and transverse directions; or there may be anumber of more limited zones of attraction which are distributedlongitudinally and/or transversely, provided that the sum of theirpartial effects upon the sheet is the same as the effects of acontinuous zone.

In accordance with the invention, the gripping system is able to movetoward and into engagement with a sheet while the preceding sheet isstill being transferred, with the result that the duration of a cycle issubstantially less than the sum of the gripping and moving times. Theunstacking rate can thus be considerably increased.

A feature of the invention is that the spacing between two sheets beingtransferred on the conveyer may be varied simply by adjusting thegripping rate. The arrangement may even be such that two successivesheets overlap over a given length that is adjustable over a wide range.This is of interest in feeding a variety of machines, and particularlycertain reheating furnaces. This feature permits dispensing withintermediate conveyers whose sole function is to regulate spacingbetween sheets.

The invention also makes it possible, by simple adjustment of theoperating rate and stroke of a plurality of gripping devices serving asingle conveying means, to feed one machine from several stacks ofsheets of different sizes while maintaining the spacing between twoconsecutive sheets constant.

In a preferred and complete form the apparatus of the invention is usedin association with an elevator table on which the sheets are stacked,and with a sheet fanner, Which may be either magnetic or pneumatic, atthe head end of the stack to fan out the head end portion of at leastthe uppermost sheets in the stack.

The lifting means advantageously is capable of upward and downwardmotion. It may, for example, consist of a magnetic roll turning freelyon its shaft, the direction of its field being radial at each point onits periphery and thus normal to the sheet at the point of contact. Thusthere will be no need to impart a rocking motion to it but merely analternating downward and upward movement.

The conveyer advantageously is a belt conveyer. The field holding thesheet on the conveyer may be produced, for example, by one or morelongitudinal, fixed magnetic rails disposed above the conveyer belt,i.e., directly above the lower course of the belt, to the lower surfaceof which the sheet is to be held. However, the magnetic field may alsobe generated by the conveyer itself, if the latter is magnetic, or by aseries of magnetic rolls.

In the drawings, FIGS. 1 to 4 show the application of the inventionschematically, and illustrate successive stages in the handling of asheet in accordance with the invention.

The apparatus comprises an elevator table 1, a stack of sheets 2 at afirst location, and a fanner 3 by which the head end portion of theuppermost sheets are fanned out. The second location to which the sheetsare to be transferred is at 4. A vertically movable magnetic liftingroll -5 is located adjacent the head end of the stack 2 in position toengage the fanned out end pontions of the sheets. Lifting magnet 6,including a magnetic roll 7, generate a magnetic field which, down tothe limit indicated by the broken line 8, is sufliciently strong tosupport a sheet from the stack 2 against the force of gravity. Aconveyer belt 9 passes around the magnetic roll 7 and anothernonmagnetic supporting roll 10 which is driven by means not shown in thedirection of the arrow.

When one of the sheets from the stack 2 is brought within the region ofthe magnetic field indicated by the broken line 8, it is supportedagainst the force of gravity in contact with the lowermost surface ofthe lower course 9a of the conveyer belt and by the movement of thatbelt is transferred to above the second location at 4. FIG. 1 shows sucha sheet 11 which is being advanced by the conveyer beyond the region ofthe magnetic field where the sheet is supported against the force ofgravity. As it passes beyond such region, successive portions of thesheet drop from the conveyer to the second location.

As shown in FIG. 2, the magnetic lifting roll 5, after having beenlowered to the position shown in dotted lines to engage the uppermost ofthe fanned out end portions of the sheets 12, has lifted such sheet fromthe stack 2 and has brought the portion from A to B into the zone ofattraction of the magnetic field wherein the force of gravity isovercome. The sheet is then attracted progressively and very rapidlyover its entire length to the conveyer by a deformation which spreadsfrom the head end to the tail end. Successive positions of the sheet areshown in FIG. 3. The solid line ABCDEF shows a first position assured bythe sheet 12, and then it rapidly deforms through succeeding positions(such as those shown in dashed lines in FIG. 3) ABC'DEF, ABC'D'EF andABCD'E'F, until it is flat against the underside of the conveyer asshown in FIG. 4. In the final position shown in FIG. 4, the sheet isadvanced by the conveyer belt to above the second location, when it willbe released as shown in FIG. 1.

The sheet may be released from the lifting roll either 'by being rolledtherefrom; or the magnetic field of the lifting roll may be momentarilyshut off. The lifting roll may begin its descent to engage the nextsheet before the preceding sheet has been advanced wholly beyond thelocation of the stack 2.

I claim:

1. Apparatus for transferring flexible sheets of ferromagnetic metalfrom a stack at a first location to a second location comprising (1) amovable conveyer disposed above and spaced from and extending betweensaid locations,

(2) magnets associated with said conveyer,

(a) said magnets establishing a magnetic field in the space between theconveyer and said locations,

(3) means for lifting, in the topmost sheet in said stack, the end ofsaid topmost sheet remote from said second location into a positionwithin said field where the lifted end of said sheet is magneticallyattracted into engagement with said conveyer and successive portions ofsaid sheet progressing toward the end of said sheet adjacent said secondlocation thereupon become magnetically attracted into engage ment withsaid conveyer until the entire sheet is held magnetically in contactwith the conveyer against the force of gravity, and

(4) means for moving said conveyer from above said first location to aposition higher than and adjacent to said second location.

2. Apparatus according to claim 1 in which the con- 'veyer is a beltconveyer and the magnets are disposed in close proximity to the conveyerbelt above the surface thereof engaged by the magnetically supportedsheets.

3. Apparatus for transferring flexible sheets of ferromagnetic metal oneby one from a stack of said sheets disposed at a first location to asecond location comprismg (l) a conveyer belt disposed above and spacedfrom and extending between said locations,

(2) magnets disposed above said conveyer belt,

(a) said magnets establishing a magnetic field in the space between theconveyer and said first location,

(3) means adjacent the end of said stack remote from said secondlocation for fanning out, in at least the uppermost sheets in the stack,the end portions thereof remote from said second location,

(4) reciprocable lifting means mounted in position to engage theuppermost of the fanned out end portions of the stack of sheets and tolift such end portion to a position within said field where it ismagnetically attracted into engagement with the conveyer belt andsuccessive portions of the uppermost sheet progressing toward the endthereof adjacent said second location thereupon become magneticallyattracted into engagement with said belt until the entire sheet is heldmagnetically against the force of gravity in engagement with theunderside of the conveyer belt, and

(5) means for moving said conveyer belt through a path of travel fromabove said first location to a position higher than and adjacent to saidsecond location.

4. The method of transferring flexible sheets of ferromagnetic metalfrom a stack at a first location to a second location which comprises(1) establishing a magnetic field extending from a position higher thanand adjacent to said first location to above said second location,

(2) lifting, in the topmost sheet of the stack, that end portion onlywhich is remote from said second location to a position within saidfield where the lifted end Portion of said sheet is magneticallysupported against the force of gravity and wherein successive portionsof said sheet progressing toward the end of said sheet adjacent saidsecond location thereupon become magnetically attracted into said fielduntil the entire sheet is supported magnetically above said firstlocation,

(3) transferring said sheet while thus supported to a position higherthan and adjacent to said second location, and

(4) advancing said sheet toward said second location beyond the regionof said magnetic field where the sheet is supported against the force ofgravity,

(a) whereby successive portions of said sheet beginning with the endthereof farthest from said first location are dropped onto said secondlocation until the entire sheet is there deposited.

5. The method of transferring flexible sheets of ferromagnetic metal oneby one from a stack of said sheets disposed at a first location to asecond location which comprises (1) establishing a magnetic fieldextending from above said first location to a position higher than andadjacent to said second location,

(2) fanning out, from at least the uppermost sheets of said stack, theend portions thereof remote from said second location,

(3) lifting the fanned out end portion only of the uppermost of thesheets in the stack to a position Within said field Where the lifted endportion of said sheet is magnetically supported against the force ofgravity and successive portions of said sheet progressing toward the endof said sheet adjacent said second location thereupon become attractedinto said field until the entire sheet is supported magnetically abovesaid first location,

(4) transferring said sheet while thus supported to a position higherthan and adjacent to said second location, and

(5) advancing said sheet toward said second location beyond the regionof said magnetic field where the sheet is supported against the force ofgravity,

(a) whereby successive portions of said sheet be- References CitedUNITED STATES PATENTS Free 271-18 Gerhardt 271l8 Chatterton 271-18"Powers 271-18 Hommel 271-18 Parke et a1 271-74 0 M. HENSON WOOD, JR.,Primary Examiner.

ALLEN N. KNOWLES, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,339,915 September 5 1967 Maurice Ricard rror appears in the above numberedpat- It is hereby certified that e s Patent should read as ent requiringcorrection and that the said Letter corrected below.

Column 4, lines 47 to 49, for "a position higher than and ad acent tosaid first location to above" read above said first location to aposition higher than and adjacent Signed and sealed this 22nd day ofOctober 1968.

(SEAL) Attest:

EDWARD J. BRENNER Commissioner of Patents Edward M. Fletcher, Ir.

Attesting Officer

1. APPARATUS FOR TRANSFERRING FLEXIBLE SHEETS OF FERROMAGNETIC METALFROM A STACK AT A FIRST LOCATION TO A SECOND LOCATION COMPRISING (1) AMOVABLE CONVEYER DISPOSED ABOVE AND SPACED FROM AND EXTENDING BETWEENSAID LOCATIONS, (2) MAGNETS ASSOCIATED WITH SAID CONVEYER, (A) SAIDMAGNETS ESTABLISHING A MAGNETIC FIELD IN THE SPACE BETWEEN THE CONVEYERAND SAID LOCATIONS, (3) MEANS FOR LIFTING, IN THE TOPMOST SHEET IN SAIDSTACK, THE END OF SAID TOPMOST SHEET REMOTE FROM SAID SECOND LOCATIONINTO A POSITION WITHIN SAID FIELD WHERE THE LIFTED END OF SAID SHEET ISMAGNETICALLY ATTRACTED INTO ENGAGEMENT WITH SAID CONVEYOR AND SUCCESSIVEPORTIONS OF SAID SHEET PROGRESSING TOWARD THE END OF SAID SHEET ADJACENTSAID SECOND LOCATION THEREUPON BECOME MAGNETICALLY ATTRACTED INTOENGAGEMENT WITH SAID CONVEYOR UNTIL THE ENTIRE SHEET IS HELDMAGNETICALLY IN CONTACT WITH THE CONVEYER AGAINST THE FORCE OF GRAVITY,AND (4) MEANS FOR MOVING SAID CONVEYER FROM ABOVE SAID FIRST LOCATION TOA POSITION HIGHER THAN AND ADJACENT TO SAID SECOND LOCATION.